System for Selective Incremental Closing of a Hydraulic Downhole Choking Valve

ABSTRACT

Systems for operating one or more sliding sleeve valves in an incremental, step-type fashion between open and closed positions, permitting the valve or valves to be choked to progressively smaller flow areas. The systems of the present invention also permit the valve or valves to be fully closed without having to progress through incremental steps.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to devices and methods for operating avalve in an incremental fashion.

2. Description of the Related Art

Sliding sleeve valves are often used in a hydrocarbon production stringto selectively control the flow of production fluid into the productionstring. A sliding sleeve valve typically includes an outer cylindricalhousing that defines a flowbore and a sleeve member that is moveablydisposed within the housing. Both the housing and the sleeve memberinclude openings. When the openings are aligned, fluid can becommunicated through the openings and into the flowbore.

SUMMARY OF THE INVENTION

The invention provides systems for operating one or more sliding sleevevalves in an incremental, step-type fashion between open and closedpositions. This permits the valve or valves to be choked toprogressively smaller flow areas. The systems of the present inventionalso permit the valve or valves to be fully closed without having toprogress through incremental steps.

In a preferred embodiment, a sliding sleeve valve is interconnected withhydraulic open and close lines so that fluid flow through the hydrauliclines will actuate the sleeve valve between open and closed positions.In preferred embodiments, the close line incorporates a fluid meteringassembly which is operable to flow discrete increments of hydraulicfluid into or out of the sleeve valve. The fluid metering assemblypreferably includes a bi-directional check valve assembly and anincremental piston assembly.

During exemplary operation of the system, the sliding sleeve valve isincrementally choked from a fully open position to a partially openposition by flowing hydraulic fluid into the close line at a pressurethat is below a predetermined level. The incremental piston assemblywill be operated to transmit a predetermined discrete amount of fluid tothe sleeve valve, thereby moving the sleeve member incrementally towarda closed position.

In the event that it is desired to fully close the sliding sleeve valve,fluid is flowed into the close line at a pressure that is above thepredetermined level. The pressurized fluid will open a check valvewithin the check valve assembly and permit fluid to pass in anunrestricted manner through the fluid metering assembly. The sleevevalve will then be shifted to a fully closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and further aspects of the invention will be readilyappreciated by those of ordinary skill in the art as the same becomesbetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings in whichlike reference characters designate like or similar elements throughoutthe several figures of the drawing and wherein:

FIG. 1 is a side, cross-sectional view of an exemplary wellborecontaining a production tubing string which incorporates sliding sleevevalves and a control system in accordance with the present invention.

FIG. 2 is a schematic side view of an exemplary sliding sleeve valve ina fully open position and an operably associated hydraulic meteringassembly, in accordance with the present invention.

FIG. 3 is a schematic side view of the sleeve valve shown in FIG. 2, nowhaving been moved to a partially choked open position.

FIG. 4 is a schematic side view of the sleeve valve shown in FIGS. 2 and3, now having been moved to a further partially choked open position.

FIG. 5 is a schematic side view of the sleeve valve shown in FIGS. 2-4now in a fully closed position.

FIG. 6 is a side, cross-sectional view of an exemplary bi-directionalcheck valve assembly used in the hydraulic metering assembly of thepresent invention

FIG. 7 is a side, cross-sectional view of an exemplary incrementalpiston assembly used in the hydraulic metering assembly of the presentinvention.

FIG. 8 is a side, cross-sectional view of the incremental pistonassembly shown in FIG. 7, now having been actuated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an exemplary wellbore 10 that that has been drilledfrom the surface 12 through the earth 14. The wellbore 10 passes throughproduction formations 16, 18 and 20, which are separated from oneanother by substantially impermeable layers 22. The wellbore 10 has beenlined with metallic casing 24, in a manner known in the art, andperforations 26 extend through the casing 24 and into the formations 16,18, 20.

A hydrocarbon production string 28 is disposed within the wellbore 10.An annulus 30 is defined between the outer radial surface of theproduction string 28 and the casing 24. The production string 28 may bemade up of sections of standard production tubing or, alternatively, beformed of coiled tubing, in a manner known in the art. The productionstring defines an interior flowbore 32 by which production fluids may beconveyed to the surface 12. The production string 28 includes productionnipples 34, 36, 38 which are located proximate each of the productionzones 16, 18, 20, respectively.

Although three production zones and three production nipples aredepicted in FIG. 1, it should be understood that this is for purposes ofillustration only, and that there may be more or fewer than three suchnipples, as needed or desired. Each of the production nipples 34, 36, 38is a sliding sleeve valve which can be opened or closed to selectivelypermit production fluid entering the wellbore annulus 30 from theperforations 26 to enter the central flowbore 32.

A common hydraulic “open” line 40 extends from a surface-based pump, oropen side fluid source, 42 and is interconnected with each of theproduction nipples 34, 36, 38 in a manner which will be described infurther detail shortly. In addition, a separate hydraulic “close” lineextends from a surface pump, or close side fluid source, 44 to each ofthe production nipples 34, 36, 38. Close line 46 extends from the pump44 to production nipple 34. Hydraulic close line 48 extends from thepump 44 to the second production nipple 36, and hydraulic close line 50extends from the pump 44 to the third production nipple 38. A hydraulicmetering assembly 52 is integrated into each of the close lines 46, 48,50. It is noted that, while the open side fluid source 42 and closedside fluid source 44 are depicted schematically as separate fluidsources, they may, in fact be a single pump or other fluid source.

FIG. 2 illustrates an exemplary sliding sleeve valve 54 of the type usedfor each of the production nipples 34, 36, 38. The sliding sleeve valve54 includes an outer cylindrical housing 56 that defines a centralflowbore 58. The housing 56 has threaded axial ends 60 to permit thehousing 56 to be integrated into the production tubing string 28.Multiple lateral flow ports 62 are disposed through the housing 56. Agenerally cylindrical sleeve member 64 is disposed within the centralflowbore 58 of the housing 56 and is axially moveable with respect tothe housing 56. Lateral fluid openings 66 are disposed through thesleeve member 64.

A radially-enlarged recess 68 is formed in a portion of the flowbore 58of the housing 56. A flange 70 extends radially outwardly from thesleeve member 64 and into the recess 68 to divide the recess 68 intofirst and second fluid chambers 72, 74. The fluid chambers 72 and 74 aredefined between the inner sleeve member 64 and the recess 68 of thehousing 56. Fluid seals 76, of a type known in the art, ensure fluidtightness for the chambers 72, 74. One of the hydraulic fluid “close”lines 46, 48 or 50 is interconnected with the first chamber 72. Thehydraulic fluid “open” line 40 is interconnected with the second chamber74.

The fluid metering assemblies 52 each include a bi-directional checkvalve assembly 78 and an incremental piston assembly 80 which areincorporated into the close line 46, 48 or 50 in a parallel fashion bythe use of fluid line splitters 82. The check valve assembly 78 is shownin greater detail in FIG. 6 and includes a housing 84 with a fluid inlet86 and a fluid outlet 88. Parallel first and second flow paths 90, 92extend from the fluid inlet 86 to the fluid outlet 88. A first checkvalve 94 is located within the first flow path 90 and is oriented so asto block fluid flow from the inlet 86 toward the outlet 88 butselectively permit fluid flow along the flow path 90 from the outlet 88toward the inlet 86. In the depicted embodiment, the first check valve94 includes a closure member 96 that is biased by compression spring 98against a valve seat 100. The spring 98 provides a bias force upon theclosure member 96 that can be overcome by a first, relatively low, levelof pressure by fluid flowing along the first flow path 90 toward inlet86. As a non-limiting example, a fluid pressure of 100-200 psi wouldunseat the closure member 96 from the valve seat 100 and allow fluid topass through the first flow path 90.

A second check valve 102 is located within the second flow path 92. Thesecond check valve 102 blocks fluid flow from the outlet 88 toward theinlet 86, but it will selectively permit fluid flow from the inlet 86toward the outlet 88. In the depicted embodiment, the second check valve102 includes a closure member 104 that is biased by a compression spring106 against a valve seat 108. The spring provides a bias force upon theclosure member 104 that can be overcome by a second level of pressure byfluid flowing along the second flow path 92 toward the outlet 88. Thesecond level of pressure is greater than the first level of pressure. Asa non-limiting example, a fluid pressure of about 5000 psi would unseatthe closure member 104 from the valve seat 108 and allow fluid to passthrough the second flow path 92.

Referring now to FIGS. 7 and 8, the incremental piston assembly 80 isshown apart from the other components of the fluid metering assembly 52.The incremental piston assembly 80 includes a tubular piston housing 110with upper and lower end subs 112, 114 secured at opposite axial ends.Fluid passages 116 are disposed axially through each of the end subs112, 114. An incremental piston chamber 118 is defined within the pistonhousing 110 between the end subs 112, 114. End sub 112 provides a fluidinlet for the chamber 118 while end sub 114 provides a fluid outlet. Thepiston chamber 118 contains an incremental piston pump, generally shownat 120. The incremental piston pump 120 is useful for sequentiallydisplacing a predetermined, known amount of fluid through the pistonchamber 118 of the incremental piston assembly 80 and includes a pistonsleeve 122 which radially surrounds a piston member 124. The exemplarypiston member 124 features an enlarged pressure-receiving end 126, areduced-diameter shaft portion 128, and an enlarged piston head 130. Itis noted, however, that the piston member 124 could have othergeometrical designs. The piston member 124 is moveable with respect tothe sleeve 122 between a retracted position (FIG. 7) and an extendedposition (FIG. 8). When moved to the extended position, the enlargedpiston head 130 of the piston member 124 displaces a volume of fluidthrough the fluid outlet 116 of end sub 114 and substantially the samevolume of fluid is drawn into the fluid inlet of end sub 112 from theclose line 46, 48 or 50. The enlarged piston head 130 of the pistonmember 124 contacts an end portion 132 of compression spring member 134,which is disposed within the chamber 88. The spring 134 biases thepiston member 124 toward the retracted position. Although the springillustrated in the drawings is a spiral-type compression spring, thoseof skill in the art will understand that other compressible springdesigns could be used, including, for example, Belleville washers orfluid springs, as are known in the art. When fluid pressure is increasedwithin the close line 46, 48, or 50, it bears upon thepressure-receiving end portion 126 to urge the piston member 124 to moveaxially with respect to the sleeve 122 toward the extended position, andthe spring member 134 is compressed by the piston head 130. It is notedthat, while the pressure-receiving end 126 of the piston member 124 maybe disposed within the surrounding sleeve 122 with a relatively closefit, there are preferably no elastomeric or other fluid-tight sealslocated between the piston member 124 and the sleeve 122. As a result,it is contemplated that some fluid pressure will seep between the pistonmember 124 and sleeve 122 during operation.

In operation, the fluid metering assemblies 52 are used to operate eachof the production nipples 34, 36, 38 by increments between an extremeopen position (i.e., the fully open position depicted in FIG. 2) and anextreme, or fully closed position (see FIG. 5). In other words, thefluid metering assemblies 52 will operate the production nipples 34, 36,38 between fully open, fully closed and partially open, or “choked”positions. It is noted that, in FIGS. 2-5, the valve is shown in a fullyopen position (i.e., the fluid openings 66 of the sleeve member 64 arefully aligned with the ports 62 of the housing 56) when the sleevemember 64 is in a raised or upper position within the housing 56, and isclosed by moving the sleeve member 64 downwardly with respect to thehousing 56, the valve 54 may be constructed so that the valve is fullyopened when the sleeve member 64 is in a lower position with respect tothe housing 56 and is shifted upwardly or even rotated with respect tothe housing for choking and closure to occur. In an exemplary method ofoperation, the production string 28 is run into the wellbore 10 andtypically secured in place with sets of packers (not shown) of a typeknown in the art. At this point, the production nipples 34, 36, 38 mayall be fully opened by pressurizing the common open line 40 withsurface-based pump, or open side fluid source, 42. This will flowpressurized fluid into the second fluid chamber 74 of each of theproduction nipples 34, 36, 38 and urge the flange 70 and sleeve 64 ofeach upwardly until each of the production nipples 34, 36, 38 are in thefully open position shown in FIG. 2. It is noted that, as fluid entersthe second chamber 74 and urges the sleeve 64 upwardly, the firstchamber 72 will be reduced in volume, and fluid within the first chamber72 will exit the first chamber 72 via the respective close lines 46, 48or 50. The fluid displaced from the first chamber 72 will flow throughthe bi-directional check valve assembly 78. In order to pass through thecheck valve assembly 78, the displaced fluid will urge closure member 96off of its valve seat 100, permitting the fluid to pass through thefirst flow path 90 of the check valve assembly 78.

When it is desired to choke the production flow into the productionnipples 34, 36, 38, the hydraulic metering assemblies 52 may be actuatedto sequentially move their respective production nipples to chokedposition of smaller flow area, as illustrated in FIGS. 3 and 4 and,eventually, the fully closed position depicted in FIG. 5. It is notedthat due to the use of separate and independent close lines 46, 48, 50for each individual production nipple 34, 36 and 38, each productionnipple may be choked separately and to a different degree than the otherproduction nipples. To choke the production nipple, fluid is flowed bypump 44 into the respective close line 46, 48 or 50 at a pressure thatis below a predetermined level. The predetermined level is the level offluid pressure that would lo unseat the closure member 104 from itsvalve seat 108 in the bi-directional check valve assembly 78. The fluidflow into the close line will cause the incremental piston assembly 80to displace a predetermined amount of fluid, as described previously,into the first chamber 72 of the respective production nipple 34, 36 or38. The predetermined amount of fluid entering the first chamber 72,will act upon the flange 70 and urge the sleeve member 64 axiallydownwardly with respect to the surrounding housing 56. From the fullyopened position shown in FIG. 2, the sleeve valve 54 will be moved tothe partially choked position shown in FIG. 3. The fluid openings 66will be less aligned with the fluid ports 62 of the housing 56, therebyreducing the amount of available fluid flow area and choking theproduction nipple 34, 36 or 38.

Once the sleeve member 64 has been moved axially downwardly in anincremental manner, as described, fluid pressure within the close line46, 48 or 50 is reduced or bled off to permit the compression spring 134of the incremental piston assembly 80 to return the piston 124 to itsretracted position. The compression spring 134 will urge the pistonmember 124 back to its retracted position. Fluid will pass around thepiston portion 126 to refill the piston chamber 118 with fluid.Following the reduction in pressure, the close line 46, 48 or 50 can berepressurized as described above to move the sleeve member 64 a furtherincremental distance axially downwardly with respect to its surroundinghousing 56. From the partially choked position shown in FIG. 3, thesleeve valve 54 will be moved incrementally to an even more chokedposition, depicted in FIG. 4. The pressure within one or more of theclose line(s) 46, 48, 50 can then again be bled off, and pressurereapplied to move the sleeve member(s) 64 of the respective productionnipple(s) 34, 36, 38 further downwardly with respect to the surroundinghousing 56, thereby further choking the flow area provided by thoseproduction nipple(s) 34, 36, 38.

The hydraulic metering assemblies 52 also may be actuated to move anassociated production nipple 34, 36 or 38 to the fully closed positionshown in FIG. 5 in a single step from either a fully opened position ora choked position. In order to do this, fluid is flowed by fluid source44 into the respective close line 46, 48 or 50 at a pressure that isabove the predetermined level necessary to unseat the closure member 104from its valve is seat 108. This permits fluid to pass in anunrestricted manner through the second flow path 92 of thebi-directional check valve assembly 78. The pressurized fluid will enterthe first chamber 72 of the production nipples 34, 36, 38, act upon theflange 70 and urge the sleeve member 64 axially downward to the fullyclosed position depicted in FIG. 5. Thus, by applying a fluid pressureto the close line(s) 46, 48, 50 at a level that is above thepredetermined fluid pressure level, the incremental piston assembly 80can be bypassed.

The foregoing description is directed to particular embodiments of thepresent invention for the purpose of illustration and explanation. Itwill be apparent, however, to one skilled in the art that manymodifications and changes to the embodiment set forth above are possiblewithout departing from the scope and the spirit of the invention.

1. A hydraulic metering assembly for operating a hydraulic device from afluid source between a fully open position and a fully closed position,the hydraulic metering assembly comprising: an incremental pistonassembly operably interconnected with the hydraulic device and operableto deliver metered amounts of fluid from the fluid source to thehydraulic device, thereby operating the hydraulic device incrementallyfrom the fully open position toward the fully closed position; and abypass mechanism to selectively permit substantially unrestricted fluidflow from the fluid source to the hydraulic device to move the hydraulicdevice to the fully closed position.
 2. The hydraulic metering assemblyof claim 1 wherein the bypass mechanism comprises a check valve thatwill open upon application of a predetermined level of fluid pressure.3. The hydraulic metering assembly of claim 1 wherein the incrementalpiston assembly comprises: a housing defining a piston chamber andhaving a fluid inlet and a fluid outlet; and a piston member moveablydisposed within the piston chamber between a retracted position and anextended position, the piston member displacing a volume of fluid fromthe piston chamber through the fluid outlet during movement from itsretracted position to its extended position.
 4. The hydraulic meteringassembly of claim 3 wherein the incremental piston assembly furthercomprises a spring for returning the piston member from its extendedposition to its retracted position.
 5. A hydrocarbon production assemblyfor use in a wellbore comprising: a hydrocarbon production string; aproduction nipple incorporated into the production string, theproduction nipple being operable between fully open, fully closed andpartially open positions; a hydraulic open line interconnecting a fluidsource with the production nipple to flow fluid from the fluid source tothe production nipple to move the production nipple toward the fullyopen position; a hydraulic close line interconnecting a fluid sourcewith the production nipple to flow fluid from the fluid source to movethe production nipple toward the fully closed position; a hydraulicmetering assembly incorporated into the close line, the hydraulicmetering assembly comprising: a) an incremental piston assembly operableto deliver metered amounts of fluid from the fluid source to theproduction nipple, thereby operating the production nipple incrementallyfrom the fully open position toward the fully closed position; and b) abypass mechanism to selectively permit substantially unrestricted fluidflow from the fluid source to the production nipple to move theproduction nipple to the fully closed position.
 6. The hydrocarbonproduction assembly of claim 5 wherein the bypass mechanism comprises acheck valve that permits fluid flow from the fluid source to theproduction nipple upon application of a fluid pressure above apredetermined level.
 7. The hydrocarbon production assembly of claim 6further comprising a check valve that permits one-way fluid flow awayfrom the production nipple.
 8. The hydrocarbon production assembly ofclaim 5 wherein the incremental piston assembly comprises: a housingdefining a piston chamber and having a fluid inlet and a fluid outlet;and a piston member moveably disposed within the piston chamber betweena retracted position and an extended position, the piston memberdisplacing a volume of fluid from the piston chamber through the fluidoutlet during movement from its retracted position to its extendedposition.
 9. The hydrocarbon production assembly of claim 8 wherein theincremental piston assembly further comprises a spring for returning thepiston member from its extended position to its retracted position. 10.The hydrocarbon production assembly of claim 5 wherein the productionnipple comprises a sliding sleeve valve comprising: an outer housingdefining an axial flowbore; a lateral fluid flow port disposed throughthe housing; a sleeve member disposed within the flowbore of the housingand having a lateral opening disposed therethrough; the sleeve memberbeing moveable with respect to the housing so that the lateral openingof the sleeve member is selectively alignable with the flow port of thehousing to provide an adjustable flow area.
 11. The hydrocarbonproduction assembly of claim 10 wherein: the flowbore of the housingprovides a recess; and the sleeve member presents a radially extendingflange that is disposed within the recess to define first and secondfluid chambers.
 12. A method for controlling a sleeve valve between anopen position and a closed position, the method comprising the steps of:associating the sleeve valve with an open side fluid source for movingthe sleeve valve to its open position; associating the sleeve valve witha closed side fluid source for moving the sleeve valve to its closedposition; incorporating a hydraulic incremental piston device betweenthe closed side fluid source and the sleeve valve, the incrementalpiston device being operable to transmit fluid to the sleeve valve indiscrete increments; moving the sleeve valve to a substantially fullyopen position; and actuating the incremental piston device to move thesleeve valve from the substantially fully open position to a partiallyopen position.
 13. The method of claim 12 further comprising the step ofbypassing the incremental piston device to move the sleeve valve to itsclosed position.